Study Of Electrifying Strategy Of Permanent Magnetic Spherical Motor Based On Torque-sharing

Traditional multi-DOF motion is driven through a large number of compleximplementations composed of multiple independent motors. Thus a high precision,multi-degree of freedom, servo controlled motors highly favored people. Sphericalmotor can simplify the system structure and improve the response speed and stability,which has very broad prospect. This paper analyzes the spherical motor developmentstatus and trends, and on the basic, relevant research is carried out on a new kind ofspherical motor.This paper describes the structure and parameters of permanent magnet sphericalmotor, and then establishes a finite element model of the motor. The motor torquecharacteristics are simulated to obtain the torque distribution of stator windings inrotor sphere. Dynamic model of permanent magnet spherical motor is established, andthe computation torque method is used to decouple the dynamic model. Consideringthe uncertainties, this paper adds compensation term to improve the robustness of thepermanent magnet spherical motor.This paper presents an electrifying strategy based on torque share method. Inorder to obtain control current of the stator winding, it requires to solving thegeneralized inverse of the torque matrix of high dimensional, which increases thecomputational burden of the control system. The target torque is decomposed into therotation torque and the tilting torque, and the torque share function is determined byrotation torque distributions. Using torque share strategy to assign the rotation torque,and the torque of each phase is secondary distributed to get the control current ofrotation movement by inverting op. On this basic, the control windings of tilt motionare determined by planning the stator sphere, which solves low-dimensional inversematrix to obtain control current of tilting motion, and reduce the computationalburden. Based on the above analysis, the control system of permanent magnetspherical motor is established for three-dimensional motion control in Matlab. Theresults prove that electrifying strategy proposed in this paper has a good effect.Using DSP and FPGA as control chip to establish hardware control system, andeach part of hardware control system is discussed. The experimental platform realizestwo closed-loops, consisting of position and speed loop outside and current loop inside. Rotation movement of permanent magnet spherical motor is realized based ontorque share strategy, which lays a good foundation for subsequent experimental oncomplex trajectory control.